A series of mesoporous xEr₂O₃·CoTiO₃ composite oxide catalysts have been prepared using a template method and tested as a new type of catalyst for the oxidative dehydrogenation of ethylbenzene to styrene by using CO₂ as a soft oxidant. Among the catalysts tested, the 0.25Er₂O₃·CoTiO₃ sample with a ratio of 1 : 4 : 4 content and calcined at 600 °C exhibited the highest ethylbenzene conversion (58%) and remarkable styrene selectivity (95%) at low temperature (450 °C).